Conventional display devices typically have a so-called panel structure produced by arranging a pair of substrates with a predetermined gap separating them and bonding them to each other with an electro optic substance such as liquid crystal held in the gap. A set of thin film transistors are formed on one of the substrates and covered by a planarizing film, on which a set of pixel electrodes are arranged, whereas an opposite electrode is arranged on the other substrate vis-a-vis the set of pixel electrodes.
In the case of a colour display device, colour filters are arranged on the so-called other substrate so as to assign the three primary display colours of red, blue and green to each of the pixel electrodes. Each pixel electrode transmits or reflects light of the wavelength of the colour assigned to it in order to cause the display device to display a desired colour image. The thickness of the layer of the electrooptic substance, which may typically be liquid crystal, of the colour display device needs to be regulated according to the wavelength of the colour assigned to each pixel so as to optimize the transmission factor or the reflection factor. However, conventional colour display devices are not provided with such a regulating function and hence it is difficult to optimally balance the three primary colours of red, blue and green on the display screen.
Active matric type display devices of the built-in drive circuit type are known. The display device of this type comprises high performance polysilicon thin film transistors to make it possible to integrally form a pixel array section and a peripheral drive circuit section on a same substrate. The pixel array section is formed by using pixel electrodes and thin film transistors for driving the pixel electrodes. The drive circuit section is also formed by using thin film transistors that are adapted to drive the pixel array section. The pixel array section and the drive circuit section formed on a same substrate are covered by a common planarizing film. Since the pixel array section and the drive circuit section are different from each other in terms of the micro-structure on the surface of the substrate, it is not always possible to uniformly planarize the two sections so that the thickness of the electrooptic substance, which may typically be liquid crystal, may locally have fluctuations to consequently degrade the quality of the displayed image.
Additionally, in the case of reflection type display devices, micro-undulations are formed on the surface of the planarizing film and light-reflecting pixel electrodes are formed thereon so that the pixel electrodes may be made to provide a desired light scattering effect. However, a special processing step needs to be introduced for forming micro-undulations on the planarizing film to complicate the manufacturing process.